Pattern projection method with charged particle beam utilizing continuous movement to perform projection

ABSTRACT

By causing a mask and a wafer to continuously move once or more and irradiating a plurality of small areas contained within a specific range of the mask in time sequence with a charged particle beam during each such continuous movement, the pattern in each small area is selectively projected onto a projection target area contained within a specific range of the wafer. The pattern to be projected onto one projection target area is divided and formed on a plurality of specific small areas contained within a specific range of the mask, and when the reduction ratio of the pattern projected from the mask onto the wafer is at 1/M, the continuous movement speed of the mask is set to be (N×M) times the continuous movement speed of the wafer (N being a real number larger than 1) and the charged particle beam to be conducted to the wafer is deflected in the direction of the continuous movement at a speed so that a relative speed of the pattern image which is projected onto the wafer and the wafer itself becomes substantially zero.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pattern projection method and aprojection system employed for lithography and the like in theproduction of semiconductor integrated circuits and, more specifically,it relates to a method and a system whereby a mask pattern is projectedonto a radiation sensitive substrate by using a charged particle beamsuch as an electron beam, an ion beam or the like.

2. Description of the Related Art

More and more research into electron beam exposure systems, whichachieve both higher resolution and higher throughput in lithography, hasbeen conducted in recent years. As an exposure method employed in thistype of system, the method whereby projection is performed for one die(corresponding to one of the many integrated circuits formed on onewafer) or for a plurality of dies, has been examined in the prior art.

However, this method causes a number of problems that must be solved,such as the difficulty in producing a mask to be used as an originaltemplate for projection and the difficulty in keeping any aberration inthe optical system within allowable limits in a large optical field ofone die or more. As a solution, the partial projection method, wherebyone or a plurality of dies are projected after being partitioned intosmaller areas has been examined recently. In this case, patternprojection is performed by deflecting an electron beam by which specificlocations on a mask and a radiation sensitive substrate such as a waferor the like are irradiated while continuously moving the mask and theradiation sensitive substrate. One should note that the deflection ofthe electron beam is performed based upon the mask position and theradiation sensitive substrate position, which are detected by a detectorsuch as a laser interferometer or the like.

With this method, since the irradiation range per shot of the electronbeam is small, it is possible to perform pattern projection at a highresolution and with a high degree of accuracy by reducing the aberrationin the optical system.

In the partial projection method described above, a mask provided withpunched holes in correspondence to the pattern form, i.e., a so-calledstencil mask, has been mainly used. However, as shown in FIG. 12, anisland pattern, in which a beam limiting area 1 (the area where thecharged particle beam is scattered or absorbed) is surrounded by apunched hole 2 for beam transmission, cannot be provided. In order toproject such an island pattern, first, the punched hole 2 in FIG. 12must be divided into two punched holes (2a and 2b, as shown in FIGS. 13Aand 13B) and they must be separately formed on separate masks 3a and 3brespectively. Then, when projecting the patterns 2a and 2b of thesemasks 3a and 3b onto a radiation sensitive substrate such as a wafer,the projection patterns must be patched together on the radiationsensitive substrate to project the punched hole 2. In this case, thethroughput is reduced due to switching of the mask 3a and 3b and theresulting activation and stoppage of the projection system.

In addition, in the projection method described above, a problem arisesin that blurring occurs in the projection pattern in the followingcases.

In the first such case, the ratio of the projection pattern projectedonto a wafer and the pattern on a mask, that is the reduction ratio, andthe ratio of the moving speed of the wafer stage and the mask stage,i.e., the drive devices for continuously moving the wafer and the maskrespectively, do not match each other.

In the second such case, when irradiating a mask with a charged particlebeam, the actual irradiation position deviates from the preset positionresulting in the image of the pattern projected onto the wafer deviatingfrom a specific position.

In the third such case, due to a delay generated between the time whenthe positions of the mask and the wafer are detected and the time whenthe electron beam is deflected, the image of the pattern projected ontothe wafer becomes deviated from a specific position.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a projection method anda charged particle beam projection system that achieve an improvement inthroughput when projecting a projection pattern to be projected onto aradiation sensitive substrate using a charged particle beam by two ormore separate projections.

Another object of the present invention is to provide a projectionmethod and a charged particle beam projection system that are capable ofeliminating the blurring and the position deviating in a projectionpattern that occur when the reduction ratio of the pattern projectionand the ratio of the moving speeds of the stages do not match, when theirradiation position of an electron beam becomes deviated or when adelay is generated at deflection of an electron beam.

In order to attain these objects:

(1) The present invention is applied to a pattern projection method inwhich a mask and a radiation sensitive substrate are each caused to makeone or more continuous movements to perform projection and, while theone continuous movement of the mask and the radiation sensitivesubstrate is being performed, a plurality of small areas containedwithin a specific range of the mask are irradiated in time sequence by acharged particle beam to selectively project a pattern in each of thesmall areas onto one of a plurality of projection areas contained withina specific range of the radiation sensitive substrate. During projectionexposure, the charged particle beam to be conducted from the mask to theradiation sensitive substrate is deflected in a direction of thecontinuous movement at a specific speed so that a relative speed of animage of the pattern which is projected onto the radiation sensitivesubstrate and the radiation sensitive substrate becomes substantiallyzero.

(2) In addition, the present invention is applied to a patternprojection method in which a mask and a radiation sensitive substrateare each caused to make one or more continuous movements to performprojection and, while the one continuous movement of the mask and theradiation sensitive substrate is being performed, a plurality of smallareas contained within a specific range of the mask are irradiated intime sequence by a charged particle beam to selectively project apattern in each of the small areas onto one of a plurality of projectionareas contained within a specific range of the radiation sensitivesubstrate. A pattern to be projected onto a projection target area ofthe radiation sensitive substrate is divided and formed on a pluralityof specific small areas contained within a specific range of the mask.

(3) Furthermore, the present invention is applied to a patternprojection method in which a mask and a radiation sensitive substrateare each caused to make one or more continuous movements to performprojection and, while the one continuous movement of the mask and onecontinuous movement of the radiation sensitive substrate are beingperformed, a plurality of small areas contained within a specific rangeof the mask are irradiated in time sequence by a charged particle beamto selectively project a pattern in each of the small areas onto one ofa plurality of projection areas contained within a specific range of theradiation sensitive substrate. (a) A pattern to be projected onto aprojection target area of the radiation sensitive substrate is dividedand formed on a plurality of specific small areas contained within thespecific range of the mask, (b) when a ratio of reduction of the patternto be projected from the mask onto the radiation sensitive substrate is1/M, a speed of the continuous movement of the mask is set at (M×N)times a speed of the continuous movement of the radiation sensitivesubstrate, the N being a real number larger than 1, and (c) duringprojection exposure, the charged particle beam to be conducted from themask to the radiation sensitive substrate is deflected in a direction ofthe continuous movement of the radiation sensitive substrate at aspecific speed so that a relative speed of the image of the patternwhich is projected onto the radiation sensitive substrate and theradiation sensitive substrate becomes substantially zero.

(4) Also, the present invention is applied to a pattern projectionmethod in which a mask and a radiation sensitive substrate are eachcaused to make one or more continuous movements to perform projectionand, while the one continuous movement of the mask and one continuousmovement of the radiation sensitive substrate are being performed, aplurality of small areas contained within a specific range of the maskare irradiated in time sequence by a charged particle beam toselectively project a pattern in each of the small areas onto one of aplurality of projection areas contained within a specific range of theradiation sensitive substrate. (a) A required time for patternprojection for the specific range of the mask from beginning to end isdetermined based upon an optimal value for irradiation time of thecharged particle beam for each of the plurality of small areas of themask and a required time for projection preparation for each of thesmall areas, (b) speeds of the continuous movements of the mask and theradiation sensitive substrate are set to ensure that the mask moves froma state in which one end of the specific range of the mask is presentwithin a mask side optical field of a projection system to a state inwhich another end of the specific range of the mask is present withinthe mask side optical field, and the radiation sensitive substrate movesfrom a state in which one end of the specific range of the radiationsensitive substrate is present in a radiation sensitive substrate sideoptical field of the projection system to a state in which another endof the specific range of the radiation sensitive substrate is presentwithin the radiation sensitive substrate side optical field, within therequired time that has been determined, and (c) during projectionexposure, the charged particle beam to be conducted from the mask to theradiation sensitive substrate is deflected in the direction of thecontinuous movements at a specific speed so that a relative speed of animage of the pattern which is projected onto the radiation sensitivesubstrate and the radiation sensitive substrate becomes substantiallyzero.

(5) Moreover, the present invention is applied to a charged particlebeam projection system provided with: drive devices that cause a maskand a radiation sensitive substrate to move continuously in a specificdirection; and a projector device that irradiates a plurality of smallareas contained within a specific range of the mask in time sequencewith a charged particle beam to selectively project a pattern in each ofthe small areas onto one of a plurality of projection areas containedwithin a specific range of the radiation sensitive substrate during oneset of continuous movements by the drive devices. The charged particlebeam projection system comprises: (a) a projection time determiningdevice that determines a required time for pattern projection for thespecific range of the mask from beginning to end, based upon an optimalvalue for a duration of irradiation of the charged particle beam foreach of the plurality of small areas of the mask and a required time forprojection preparation for each of the small areas; (b) a continuousmovement speed setting device that sets speeds of continuous movementsof the mask and the radiation sensitive substrate to ensure that themask moves from a state in which one end of the specific range of themask is present within a mask side optical field of a projection systemto a state in which another end of the specific range of the mask ispresent within the mask side optical field, and the radiation sensitivesubstrate moves from a state in which one end of the specific range ofthe radiation sensitive substrate is present within a radiationsensitive substrate side optical field of the projection system to astate in which another end of the specific range of the radiationsensitive substrate is present within the radiation sensitive substrateside optical field, within the required time determined by theprojection time determining device; and (c) a speed differenceeliminating device that deflects the charged particle beam to beconducted from the mask to the radiation sensitive substrate in thedirection of the continuous movements at a specific speed so that arelative speed of an image of the pattern which is projected onto theradiation sensitive substrate and the radiation sensitive substratebecomes substantially zero during projection exposure.

(6) Also, the present invention is applied to a pattern projectionmethod in which a radiation sensitive substrate is caused to make one ormore continuous movements to perform projection and during the onecontinuous movement of the radiation sensitive substrate a plurality ofsmall areas contained within a specific range of a mask are irradiatedby a charged particle beam to selectively project a pattern in each ofthe small areas onto one of a plurality of projection areas containedwithin a specific range of the radiation sensitive substrate. (a) Arequired time for pattern projection for the specific range of theradiation sensitive substrate from beginning to end is determined basedupon an optimal value for a duration of irradiation of the chargedparticle beam for each of the projection target areas of the radiationsensitive substrate and a time required for projection preparation foreach of the projection target areas, (b) a speed of the continuousmovement of the radiation sensitive substrate in which one end of thespecific range of the radiation sensitive substrate is present within anoptical field of a projection system at the radiation sensitivesubstrate side to a state in which another end of the specific range ofthe radiation sensitive substrate is present within the optical field atthe radiation sensitive substrate side within the required time that hasbeen determined, and (c) during projection exposure, the chargedparticle beam to be conducted from the mask to the radiation sensitivesubstrate is deflected in a direction of the continuous movement at aspecific speed so that a relative speed of an image of the pattern whichis projected onto the radiation sensitive substrate and the radiationsensitive substrate becomes substantially zero.

(7) In addition, according to the present invention, since a pattern inone small area of the mask is projected onto a plurality of specificprojection target areas contained within the specific range of theradiation sensitive substrate, the mask size can be reduced.

(8) Furthermore, the present invention is applied to a charged particlebeam projection system provided with a drive device that causes aradiation sensitive substrate to move continuously in a specificdirection, and a projector device that irradiates a plurality of smallareas contained within a specific range of the mask in time sequencewith a charged particle beam to selectively project a pattern in each ofthe small areas onto one of a plurality of projection areas containedwithin a specific range of the radiation sensitive substrate during onecontinuous movement by the drive device. The charged particle beamprojection system comprises: (a) a projection time determining devicethat determines a required time for pattern projection for the specificrange of the radiation sensitive substrate from beginning to end basedupon an optimal value for a duration of irradiation of the chargedparticle beam for each of the plurality of target areas of the radiationsensitive substrate and a time required for projection preparation foreach of the target areas; (b) a continuous movement speed setting devicethat sets a speed of continuous movement of the radiation sensitivesubstrate driven by the drive device to ensure that the radiationsensitive substrate moves from a state in which one end of the specificrange of the radiation sensitive substrate is present in an opticalfield of the projection system at the radiation sensitive substrate sideto a state in which another end of the specific range of the radiationsensitive substrate is present within the optical field at the radiationsensitive substrate side within the required time determined by theprojection time determining device; and (c) a speed differenceeliminating device that deflects the charged particle beam to beconducted from the mask to the radiation sensitive substrate in thedirection of the continuous movement at a specific speed so that arelative speed of an image of the pattern which is projected onto theradiation sensitive substrate and the radiation sensitive substratebecomes substantially zero during projection exposure.

(9) Furthermore, the present invention is applied to a charged particlebeam projection system that detects positions of a mask and a radiationsensitive substrate which make continuous movements and, based uponvalues thereby detected, project a pattern of the mask onto theradiation sensitive substrate by deflecting a charged particle beam. Thecharged particle beam projection system comprises: a correction devicethat corrects a positional deviation of a projected pattern caused by afirst delay from a time when the position of the mask is detected untilthe charged particle beam by which the mask is irradiated is deflectedand a second delay from a time when the position of the radiationsensitive substrate is detected until the charged particle beam by whichthe radiation sensitive substrate is irradiated is deflected.

(10) In a charged particle beam projection system according to thepresent invention, the correction device corrects a positional deviationof a projected pattern caused by a positional deviation between airradiation position on the mask which should be irradiated by thecharged particle beam and a irradiation position at which irradiation isactually performed with the charged particle beam, in addition toperforming positional deviation correction for a projected patterncaused by the first delay and the second delay.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D show an example of a mask and a radiation sensitivesubstrate used in a first embodiment of the pattern projection methodaccording to the present invention, with FIG. 1A being a plan view ofthe mask and FIG. 1B being a plan view of the radiation sensitivesubstrate, FIG. 1C being an enlargement of the Ic portion in FIG. 1A andFIG. 1D being an enlargement of the Id portion of FIG. 1B.

FIGS. 2A and 2B show an example of the mask with FIG. 2A being a planview of a small area and FIG. 2B being a cross section taken along line2B--2B in FIG. 2A;

FIGS. 3A and 3B illustrate the continuous movements of the mask and theradiation sensitive substrate in the first embodiment, with FIG. 3Ashowing a case in which the distances traveled by the mask and theradiation sensitive substrate are set at the maximum and FIG. 3B showinga case in which the distances traveled by the mask and the radiationsensitive substrate are set at the minimum;

FIGS. 4A and 4B show variations of the method illustrated in FIGS.1A-1D;

FIGS. 5A and 5B show another variation of the mask and radiationsensitive substrate;

FIG. 6 schematically shows an embodiment of the projection systemaccording to the present invention;

FIG. 7 is a flowchart illustrating the processing for determining thecontinuous movement speeds that are executed by the control device shownin FIG. 6;

FIG. 8 is a flowchart illustrating the processing for determining thedeflection speed that is executed by the control device shown in FIG. 6;

FIGS. 9A and 9B show a second embodiment of the pattern projectionmethod according to the present invention and illustrate a positionaldeviation of the pattern image caused by the "delay";

FIG. 10 illustrates the irradiation position deviation of the electronbeam on a mask;

FIG. 11 illustrates the scanning with a spot beam;

FIG. 12 shows an island pattern;

FIGS. 13A and 13B show an example in which the island pattern shown inFIG. 12 is divided into two portions to be provided on masks; and

FIGS. 14A-14C show reference examples for comparison against the patternprojection method according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIGS. 1A-1D illustrate the pattern projection method according to thepresent invention, and show small areas 110 of a mask 10 and projectiontarget areas 210 of a radiation sensitive substrate 20. FIG. 1A is aplan view of the mask 10, FIG. 1B is a plan view of the radiationsensitive substrate 20, FIG. 1C is an enlargement of the Ic portion inFIG. 1A and FIG. 1D is an enlargement of the Id portion in FIG. 1B. Themask 10 and the radiation sensitive substrate 20 are respectivelyprovided with four rows each of specific ranges 11 and 21. The smallareas 110 on the mask 10 constitute an area of one shot of irradiationwith, for instance, a charged particle beam and while the mask 10 iscaused to move continuously once in either the left or right directionin FIG. 1A, the pattern within each of a specific ranges 11 is projectedonto a corresponding specific range 21 of the radiation sensitivesubstrate 20.

FM and FW respectively indicate the optical fields on the mask 10 andthe radiation sensitive substrate 20, and these are the ranges overwhich pattern projection can be performed at a specific degree ofaccuracy with finite broadening around the optical axis AX of thecharged particle beam optical system. The areas outside of the opticalfields FM and FW are not used for projection. It is to be noted that thenumber of rows can be changed as necessary. When a plurality of rows arepresent, stepping drive is performed for the mask 10 and the radiationsensitive substrate 20 in the direction running at a right angle to thedirection of the continuous movement every time the projection of onerow is completed and the rows in a specific ranges 11 and 21 that areadjacent to the previous rows are positioned to the optical fields FMand FW in the projection system. As indicated with the arrows YM and YM'in FIG. 1A, the direction of the continuous movement is switched foreach row. In FIG. 1A and FIG. 1B the areas of the optical fields FM andFW are indicated as square shapes. However the area using for exposureis not limited to a square shape. For example, the area can be arectangular shape. And if the direction running at a right angle to themoving direction of a stage is assigned as a long side of therectangular shape, the length of this long side can be made longer thanthe length of the square shape. This can cause a reduction of the numberof rows of the specific ranges 11. Accordingly, the throughput can beimproved.

A pattern to be projected onto one of the projection target areas, i.e.,the projection target area 210a of the radiation sensitive substrate 20shown in FIG. 1D is partitioned into a plurality of patterns and theplurality of patterns are formed on a plurality of small areas includedin one specific range 11 of the mask 10, respectively, i.e., on smallareas 110a1 and 110a2 in FIG. 1C, for instance. A specific range 11 hererepresents a range over which a pattern can be projected while the mask10 continuously moves once. Such partitioning becomes necessary whenprojecting an island pattern such as the one shown in FIG. 12, forinstance, but partitioning can be implemented as necessary in othercircumstances as well. For instance, when the pattern (beam transmissionarea) density is high in a small area 110, there is a likelihood thatblurring will occur in the pattern image due to the Coulomb effect. Thepattern in a small area 110 may be formed at the mask 10 by dividing itinto a plurality of patterns in such a case. When a pattern ispartitioned in this manner, the patterns in the small areas 110a1 and110a2 are projected in the same projection target area 210a.

On the supposition that the number of projection target areas 210 in onespecific range 21 of the radiation sensitive substrate 20 is P and thatthe pattern in each projection target area 210 is partitioned into twoand is formed on two small areas 110 of the mask 10, the number of smallareas 110 contained in one specific range 11 is 2P. With the timerequired for projecting the pattern in one small area 110 set at ts, theminimum length of time required for pattern projection of one specificrange 21 of the radiation sensitive substrate 20 is 2Pts.

Now, let us consider a case in which, as shown in FIGS. 14A-14C, one ofthe two small areas 110a1 and 110a2 corresponding to one projectiontarget area 210 is formed in one specific range 11A of the mask 10 andthe other small area is formed in another specific range 11B of the mask10, for comparison. In this case, too, if each specific range 21 of theradiation sensitive substrate 20 is provided with P projection targetareas 210 and the pattern in each projection target area 210 ispartitioned and then formed over two small areas 110 of the mask 10, theminimum length of time required for projecting the pattern over theentirety of one specific range 21 is 2Pts, as in the case describedabove.

However, although, in the case presented in FIGS. 1A-1D, the small areas110a1 and 110a2 corresponding to one projection target area 210a areincluded in the same specific range 11, in the case presented in FIGS.14A-14C, the small area 110a1 and the small area 110a2 are included inspecific ranges 11A and 11B respectively. Because of this, whenprojecting the pattern in the small areas 110a1 and 110a2 of the mask 10onto the projection target area 210a, the pattern in the small area 110a1 included in a specific range 11A must be first projected and then thepatterns in the small area 110a2 included in a specific range 11B mustbe projected by reversing the direction of the continuous movements ofthe mask 10 and the radiation sensitive substrate 20.

As a result, in the case presented in FIGS. 14A-14C, the number of rowsof specific ranges is double that in the case presented in FIGS. 1A-1D,requiring twice as many scanning sessions. In addition, dead time,during which no projection is performed, occurs due to the starting andstopping of the device for causing the mask 10 to move, the switching ofthe moving direction and the acceleration time before the speed of thecontinuous movement reaches a specific value. This dead time is almosthalved in the case presented in FIGS. 1A-1D compared to the casepresented in FIGS. 14A-14C.

Thus, since, when projecting a pattern divided and then provided over aplurality of small areas of the mask 10 onto one projection target areaon the radiation sensitive substrate, these pluralities of small areasare included in a specific range which constitutes a range over whichprojection is possible in one continuous movement, the dead timeresulting from looping back the mask and the like is minimized, makingit possible to achieve a high throughput.

FIGS. 2A and 2B show an example of the mask 10, with FIG. 2A being aplan view showing a small area 110 and FIG. 2B being a cross sectiontaken along line 2B--2B in FIG. 2A. In FIGS. 2A and 2B, reference number120 indicates struts for mechanically fortifying the mask 10 and a skirt130 which constitutes a charged particle beam screening area providedbetween the struts 120 and the small areas 110. Reference number 140indicates a range of irradiation of the charged particle beam. Since thestrut 120, the skirt 130 and the like are provided in addition to thesmall area 110, the length of a specific range 11 of the mask 10 inregard to the direction of the continuous movement, is larger than theinverse multiple of the reduction ratio 1/M of the pattern imagerelative to the length of a specific range 21 of the radiation sensitivesubstrate 20.

As indicated with the solid lines in FIGS. 3A and 3B, all the smallareas 110 within a specific range 11 can be irradiated by a chargedparticle beam with a high degree of efficiency by ensuring that theradiation sensitive substrate travels in the direction indicated withthe arrow YW from a state in which one end 21a of the radiationsensitive substrate 20 has entered the optical field FW of theprojection system at the radiation sensitive substrate side to a statein which another end 21b has entered the optical field FW at theradiation sensitive substrate side while the mask 10 travelscontinuously in the direction indicated with the arrow YM from a statein which one end 11a of the mask 10 has entered an optical field FM ofthe projection system at the mask side to a state in which the other end11b of the mask 10 has entered the optical field FM at the mask.Consequently, it is essential that the continuous movement speed VM ofthe mask 10 during projection be set at N·M times (N being a real numberlarger than 1) the continuous movement speed VW of the radiationsensitive substrate 20.

Since the moving speed Vimage of the pattern image to be projected ontothe radiation sensitive substrate 20 is 1/M times the moving speed Vm ofthe mask 10 with the reduction ratio being 1/M, i.e., vimage=VM/M, itdoes not match the moving speed VW=VM/(N·M) of the radiation sensitivesubstrate 20 explained above. If this is left as is, blurring occurs inthe pattern image to be projected onto the radiation sensitive substrate20 due to the difference in their speeds.

In order to avoid this, during the continuous movement, the chargedparticle beam to be conducted from the mask 10 to the radiationsensitive substrate 20 is deflected in the direction of the continuousmovement at a specific speed so that the speed of the pattern imagerelative to the radiation sensitive substrate 20 is 0. It is desirableto perform this deflection operation using an electrostatic deflectorwith outstanding response.

Either of the following two methods may be employed for determining thedeflection speed during the continuous movement in this process.

In the first method, the continuous moving speed VM of the mask 10 andthe continuous moving speed VW of the radiation sensitive substrate 20are detected during the projection and the deflection speed VWD isdetermined based upon the detected values and the reduction ratio of theimage 1/M, using the following expression (1).

    VWD=VW-(VM/M)                                              (1)

For the speed VM, the direction in which the image projected on theradiation sensitive substrate 20 advances in the direction of thecontinuous movement of the radiation sensitive substrate 20 is set as apositive direction and for the speeds VW and VWD, the direction of thecontinuous movement of the radiation sensitive substrate 20 is set as apositive direction. It is to be noted that when an error in thedirection of the continuous movement, i.e., the angle θ formed by thevectors of the speeds VM and VW can also be detected, the followingexpression (2) is used.

    VWD=VW-(VM/M)cos θ                                   (2)

It is to be noted that the speed may be calculated based upon the valuesobtained by detecting the displacement and acceleration of the mask 10and of the radiation sensitive substrate 20 as physical quantitiesrelated to the speeds instead of directly detecting the speeds VM andVW.

In the second method, the continuous movement speeds of the mask 10 andthe radiation sensitive substrate 20 are calculated based upon thesensitivity of the resist applied on the radiation sensitive substrate20, the beam current density of the charged particle beam, the blankspace in the mask 10 (the boundary areas between small areas and thelike), the number of times projection is performed and the like, and thedeflection speed is determined based upon the calculated value and thereduction ratio of the image. The details are given below.

When the irradiation time required for irradiating the entirety of onespecific range 11 of the mask 10 with a charged particle beam (includingthe irradiation stop time for switching small areas to be irradiated) isdesignated TM and the pattern projection time required for projecting apattern onto the entirety of one specific range 21 of the radiationsensitive substrate 20 is designated TW, they are equal to each other,i.e., TM=TW=T. It must be ensured that the projection of the pattern fora specific ranges 11 and 21 be completed within this time period T.Namely, the continuous movement speed VM of the mask 10 is set so thatthe mask 10 moves from a state in which one end 11a of the one specificrange 11 is present in the optical field FM at the mask side to a statein which the other end 11b of a specific range 11 is present in theoptical field FM at the mask side within the time T explained above.

At this point, the mask 10 moves as shown in FIGS. 3A and 3B. FIG. 3Aillustrates a case in which the distances traveled by the mask 10 andthe radiation sensitive substrate 20 are at their maximum, whereas FIG.3B illustrates a case in which the distances traveled by the mask 10 andthe radiation sensitive substrate 20 are at their minimum, and thetraveling distances may be set within these ranges. As these figuresclearly demonstrate, when the entire length of a specific range 11 ofthe mask 10 is designated LM, the width of the optical field FM at themask side in the direction of the continuous movement is designated LFMand the width of the small area at the mask side in the direction of thecontinuous movement is designated SM, and with the maximum and minimumvalues for the traveling distances mentioned above taken intoconsideration, the mask 10 only needs to travel over a distance Laexpressed in the following expression (3) within the time T explainedabove.

    La=LM+LFM-2SM

    through La=LM-LFM                                          (3)

The same concept applies to the radiation sensitive substrate 20. Whenthe entire length of a specific range 21 is designated LW, the width ofthe optical field FW at the radiation sensitive substrate side in thedirection of the continuous movement is designated LFW and the width ofthe projection target area 210 at the radiation sensitive substrate sidein the direction of the continuous movement is designated SW, theradiation sensitive substrate 20 only needs to travel over a distance Lbexpressed in the following expression (4) within the specific timeperiod T explained earlier.

    Lb=LW+LFW-2SW

    through Lb=LW-LFW                                          (4)

Thus, the speeds VM and VW of the continuous movement are:

    VM=La/T

    VW=Lb/T                                                    (5)

Since, in these expressions, T is the length of time required forpattern projection onto a specific range 11,

    T=Σts+Σtbs                                     (6)

Note that ts is the optimum value for the duration of irradiation of thecharged particle beam for one small area 110, and when the sensitivityof the resist applied to the radiation sensitive substrate 20 isdesignated S (μC/cm²) and the beam current density of the chargedparticle beam is designated A (μ/cm²), it can be expressed in thefollowing expression (7).

    ts=S/A                                                     (7)

tbs represents the preparation time elapsing after irradiation of thecharged particle beam for one small area 110 ends until irradiation ofthe charged particle beam for the next small area 110 begins. Note thatthe period of irradiation time of the charged particle beam may vary foreach small area 110 due to correction for the proximity effect and thelike. In addition, depending upon the distance that the beam travelswhen switching the object of the irradiation of the charged particlebeam from one small area 110 to the next small area 110, the preparationtime tbs may also vary. Furthermore, if multi-shot irradiation isperformed, the number of times the preparation time tbs is addedincreases.

In any case, the values of ts and tbs can be determined based upondesign data and the like of the pattern of the mask 10. With thecontinuous movement speeds VM and VW determined in the manner describedabove, the deflection speed VWD can be calculated using those values andthe reduction ratio 1/M with the expression (1) given earlier.

However, since deviations may occur between the deflection speed and thecontinuous movement speeds that have been calculated and set, and theactual speed, it is desirable to determine the deflection speed byemploying the first method, in which VM and VW are actually detected. Itis to be noted that even when the first method is employed, the settingof the continuous movement speeds for the mask 10 and the radiationsensitive substrate 20 is performed using the second method.

Thus, in the projection method described above, since the chargedparticle beam is deflected during the continuous movement in such amanner that the speed of the pattern image to be projected onto theradiation sensitive substrate relative to the radiation sensitivesubstrate is 0, projection without blurring can be performed with a highdegree of precision.

It is to be noted that in the FIGS. 1A-1D, the small areas 110a1 and110a2 are provided adjacent to each other in the direction of thecontinuous movement, they may be arranged as shown in FIGS. 4A and 4B,for instance. FIGS. 4A and 4B respectively correspond to FIGS. 1C and1D, and the pattern in one projection target area 210b of the radiationsensitive substrate 20 is divided and then provided over a pair of smallareas 110b1 and 110b2 adjacent to each other in the direction (thevertical direction in the figures) running at a right angle to thedirection of the continuous movement on the mask 10. The pattern in aprojection target area 210c, which is adjacent in the direction runningat a right angle to the direction of the continuous movement, is dividedand then provided over two small areas 110c1 and 110c2 adjacent to thesmall areas 110b1 and 110b2 in the direction of the continuous movement.

While the explanation has been given in reference to FIGS. 1A-1D andFIGS. 4A and 4B, for a case in which a pattern formed over two smallareas contained within a specific range 11 of the mask 10 is projectedonto one projection target area in a specific range 21 of the radiationsensitive substrate 20, the present invention may be adopted in a casein which a pattern in one small area contained within a specific range11 of the mask 10 is projected onto a plurality of projection targetareas contained within a specific range 21 of the radiation sensitivesubstrate 20, and such an example is shown in FIGS. 5A and 5B.

In FIGS. 5A and 5B, which correspond to FIGS. 1A and 1B respectively, apattern formed in a small area 110a of the mask 10 is projected ontoprojection target areas 210a1 and 210a2 of the radiation sensitivesubstrate 20. While the pattern is projected onto two projection targetareas that are provided contiguously in the direction of the continuousmovement of the substrate 20 (direction YW) in FIG. 5B, the presentinvention may be adopted in a similar manner in a case in whichprojection is performed onto projection target areas providedcontiguously in a direction running at a right angle to the direction ofthe continuous movement. In either case, since the number of times thedirection of the continuous movement of the mask 10 and the radiationsensitive substrate 20 are switched is the same as that of the casesshown in FIGS. 1A-1D, FIGS. 3A and 3B, and FIGS. 4A and 4B, a highthroughput is achieved.

When projection is performed in the manner illustrated in FIGS. 5A and5B, since the pattern in the small area 110 is used in correspondence toa plurality of projection target areas 210, the size of the mask can bereduced and production is facilitated compared to a case in which thesmall area 110 is made to correspond to one specific projection targetarea 210. In addition, since the moving speed of the mask stage can alsobe reduced, the cost of system production can be reduced.

Furthermore, by performing projection in this manner, if the number ofsmall areas 110 of the mask 10 is small enough for the mask 10 to becontained within the optical field FM at the mask side, projection canbe performed without moving the mask 10. In this case, only the stage ofthe radiation sensitive substrate is caused to move continuously toperform projection, while the mask stage remains stationary. One shouldnote that when moving to a different specific range 11, the mask stageis caused to move in steps in a direction running at a right angle tothe direction of the continuous movement.

FIG. 6 shows a schematic structure of an embodiment of the electron beamreduction projection system according to the present invention. In thefigure, the z axis is set in the direction running parallel to theoptical axis AX of the optical system. The direction of the x axismatches the direction of the continuous movement of the mask 10 and awafer 20A (which corresponds to the radiation sensitive substrate 20 inFIGS. 1A-1D and FIGS. 5A and 5B). In FIG. 6, reference number 31indicates an electron gun and an electron beam EB discharged from thisgun is focused by condenser lenses 32 and 33 and is shaped into a beamwith a rectangular cross section by a first aperture 34. The shapedelectron beam EB is adjusted to become parallel to the optical axis AXby a condenser lens 35, is deflected by a specific quantity atdeflectors 36A and 36B provided over two stages and enters a specificarea of the mask 10, which is mounted on a mask stage 37. The deflector36A is constituted by combining two sets of deflecting coils thatgenerate deflecting magnetic fields extending in a specific directionrunning at a right angle to the optical axis AX in such a manner thattheir deflecting directions are different from each other. By adjustingthe value of the electrical current supplied to each set of thedeflecting coils in the deflector 36A, the electron beam EB can bedeflected in any direction within a plane running at a right angle tothe z axis. This is also the case with the deflectors 36B. The maskstage 37 is driven in the direction of the x axis and the direction ofthe y axis by an actuator 61. As explained earlier in reference to FIGS.1A-1D and FIGS. 3A and 3B, the mask 10 is provided with at least one rowconstituting a specific range 11 with a plurality of small areas 110contained in it. A pattern to be projected onto one projection targetarea 210 of the wafer 20A is divided and then formed over at least someof the small areas 110.

The electron beam EB, having been transmitted through the mask 10 entersthe wafer 20A, which is mounted on a wafer stage 40, at a specificposition after passing through projecting lenses 38 and 39 provided overtwo stages. The projecting lenses 38 and 39 constitute an opticalreduction system and its reduction ratio may be set at 1/4, forinstance. The wafer stage 40 is driven in the directions of the x axisand the y axis by an actuator 62. Deflectors 41A and 41B provided overtwo stages for adjusting the entry position of the electron beam intothe wafer 20A are provided between the mask stage 37 and the wafer stage40. The schematic structure of the deflectors 41A and 41B is identicalto that of the deflectors 36A and 36B. A second aperture 42, whichprevents the electron beam that has been scattered over a specificquantity by the mask 10 from entering the wafer 20A, is provided in thevicinity of the cross-over CO of the electron beam imparted by theprojecting lenses 38 and 39.

In addition, an electrostatic deflector 43 is provided between thesecond aperture 42 and the wafer stage 40. The electrostatic deflector43 is provided with a pair of electrodes which flank the optical axis AXin the direction of the x axis and deflect the electron beam EB in thedirection of the x axis, i.e., in the direction of the continuousmovement of the mask 10 and the wafer 20A, by generating a voltagedifference between the pair of electrodes.

Noted that for convenience, the electrodes are shown facing oppositeeach other in the direction of the y axis in the figure. Referencenumber 44 indicates a laser interferometer position sensor which detectsthe position of the mask stage 37 in the directions of the x axis andthe y axis and reference number 45 indicates a laser interferometerposition sensor that detects the position of the wafer stage 40 in thedirections of the x axis and the y axis. The information detected bythese position sensors 44 and 45 is input to a control device 50 whichalso functions as the projection time determining device and thecontinuous movement speed setting device.

A control power supply 51 for the condenser lenses 32, 33 and 35, acontrol power supply 52 for the deflectors 36A and 36B, a control powersupply 53 for the deflectors 41A and 41B, a control power supply 54 forthe projecting lenses 38 and 39, a control power supply 55 for theelectrostatic deflector 43 and the actuators 61 and 62 are connected tothe control device 50. The output currents from the individual controlpower supplies 51-54 and the output voltage from the control powersupply 55 are controlled by the control device 50. By controlling theactuators 61 and 62, the control device 50 also controls the movementsof the mask stage 37 and the wafer stage 40.

Reference number 56 indicates a storage device for the control device50. During the preparatory stage prior to projection, projection datarequired for various types of control to be performed during projectionare input from an input device 57 to the control device 55 and arestored in the storage device 56. These projection data include thereduction ratio 1/M, the distances La and Lb traveled by the mask 10 andthe wafer 20A, the irradiation time ta of the electron beam for eachsmall area 110, the preparation time tbs, the resist sensitivity S andthe beam current density A as values necessary for the calculation ofthe expressions (1)-(7) explained earlier. In addition, information onthe corresponding relationship between the individual small areas 110 ofthe mask 10 and the projection target areas 210 of the wafer 20A, i.e.,the information in regard to which projection target area 210 of thewafer 20A the pattern in each small area 110 should be projected to, isalso provided in advance as projection data.

When the projection data are stored in the storage device 56, thecontrol device 50 calculates the continuous movement speeds VM and VWduring projection by following the procedure shown in FIG. 7. In thisprocessing, which is performed by using the expressions (5) and (6)explained earlier, the projection data are read in step SP1 and in stepSP2 the projection time T over one continuous movement is determinedusing the expression (6). In step SP3, the speeds VM and VW of thecontinuous movement are calculated using the expression (5) and in stepSP4, the speeds VM and VW are stored in the stored device to end theprocessing. It is to be noted that the processing described above may beperformed by a device other than the projection system with the resultsbeing provided to the projection system.

When a command for projection start is issued to the control device 50through an operation by an operator or the like, the control device 50starts projection in conformance to the projection data. At this point,the operations of the mask stage 37 and the wafer stage 40 arecontrolled to ensure that the mask 10 and the wafer 20A movecontinuously at the speeds VM and VW, advancing in directions oppositefrom each other in the direction of the y axis. If a plurality ofspecific ranges 11 and 21 are provided in rows on the mask 10 and thewafer 20A, every time one continuous movement ends, the mask stage 37and the wafer stage 40 are driven in steps in the direction of the yaxis, which runs at a right angle to the direction of the continuousmovement, and specific ranges 11 and 21 which are the object of the nextprojection are respectively brought into the optical field at the maskside and into the optical field at the wafer side respectively.

During one session of the continuous movement, a plurality of smallareas 110 contained within a specific range 11 for which projection isto be performed are irradiated by the electron beam EB, in a specificorder, and the electron beam passing through each small area 110 isconducted to a specific position on the wafer 20A. At this point, theirradiation position of the electron beam EB relative to the mask 10 isadjusted by the deflectors 36A and 36B and the pattern projection targetposition relative to the wafer 20A is adjusted by the deflectors 41A and41B. In addition, in order to ensure that there is no difference inspeed between the pattern image and the wafer 20A, the deflection speeddetermining processing shown in FIG. 8 is interrupt-executed at anappropriate cycle.

In the processing shown in FIG. 8, first, the actual the continuousmovement speeds (hereafter referred to as actual speeds) VMa and VWa ofthe mask 10 and the wafer 20A are detected by differentiating the stagepositions detected by the laser interferometer position sensors 44 and45 in step SP11. Note that since the position sensors 44 and 45 bothdetect the bidirectional positions in the directions of the x axis andthe y axis, any error between directions of the actual speeds VMa andVwa within the x-y plane is also determined. In step SP12, thedeflection speed VWD is determined by substituting the actual speeds VMaand VWa and the directional error θ in the expression (2). Next, in stepSP13, the voltage at the electrostatic deflector 43 is set to ensurethat the electron beam EB is deflected in the direction of thecontinuous movement at the calculated deflection speed VWD, and then theoperation returns to step SP11 to repeat the processing described above.Note that the processing shown in FIG. 8 may also be executed constantlyby a control circuit specially provided for this purpose. The voltagecontrol for the electrostatic deflector 43 should employ an analogmethod or a digital method with sufficiently fine increments.

While the speeds of the continuous movement are determined based uponthe positional information detected by the laser interferometer positionsensors 44 and 45 in the embodiment described above, the speeds of themask 10 and the wafer 20A may be directly detected or the accelerationof the mask 10 and the wafer 20A may be integrated. If the errors in thecontinuous movement speeds of the mask 10 and the wafer 20A are smallenough, the processing shown in FIG. 8 may be omitted and the deflectionspeed may be determined using the expression (1) in the processing shownin FIG. 7.

Second Embodiment

In the second embodiment, which is to be explained below, the blurringdescribed in (a) and (b) below can be prevented.

(a) Blurring in the projection pattern caused by the "delay" from thetime when the stage positions are detected by the position sensors 44and 45 until the electron beam EB is deflected, and by deviation of theirradiation position of the electron beam EB on the mask 10.

(b) Blurring in the projection pattern caused by a deviation in theirradiation position of the electron beam EB on the mask 10.

First, in reference to FIGS. 9A and 9B, a method for preventing blurringwhen there is a "delay" is explained. FIGS. 9A and 9B schematically showthe positional relationship between the mask 10 and the wafer 20A, and adeflector 41 represents the pair of deflectors 41A and 41B shown in FIG.6. In FIGS. 9A and 9B, portions that are not essential for theexplanation have been omitted. The length of time elapsing after thepositions of the stages 37 and 40 (see FIG. 6) have been detected by theposition sensors 44 and 45 until the electron beam EB is deflected bythe detectors 36A, 36B,41A and 41B, i.e., the delay times are designatedΔtM and ΔtW respectively. The expression "the positions of the mask 10and the wafer 20A are detected by the position sensors 44 and 45" isused in the following explanation since the positions of the mask 10 andthe wafer 20A can be obtained by detecting the positions of the stages37 and 40 by the position sensors 44 and 45.

FIG. 9A illustrates a case in which ΔtM is not equal to 0, and ΔtW=0.Reference number 120 indicates the position at which detection isperformed by the position sensors 44 and 45 with the value detected bythe position sensor 44 being M1 and the value detected by the positionsensor 45 being W1 at the current time point (time point t0). However,since ΔtM is not equal to 0, the deflection of the electron beam EB bythe deflector 41 is performed based upon position M0 of the mask 10detected by the position sensor 44 at the time point (t0-ΔtM). In FIG.9A, a chain double-dashed line 10' indicates the mask position at thetime point (t0-ΔtM). In other words, the deflector 41 always responds byshifting in time (being delayed) by ΔtM. Because of this, the image ofthe pattern at position M1 of the mask 10, which should be projected atposition W1, i.e., the projection target position on the wafer 20A, endsup being irradiated at position W0 through the path indicated with thebroken line in the figure.

In the case in which ΔtM=0 and ΔtW is not equal to 0, as shown in FIG.9B, the deflection of the electron beam EB by the deflector 43 isperformed based upon position W0 of the wafer 20A detected by theposition sensor 45 at the time point (t0-ΔtW). In FIG. 9B, the chaindouble-dashed line 20A' indicates the wafer position at time point(t0-ΔtW). In other words, the deflector 43 always responds, by shiftingin time (being delayed) by ΔtW. Because of this, the pattern image whichshould be projected at position W1 of the wafer 20A, which is theprojection target position, ends up being projected at position W2through the path indicated with the broken line in the figure.

To deal with this problem, the electron beam EB is deflected using adeflector 43 in the following manner in the present invention. In thecase illustrated in FIG. 9A, the electron beam EB is deflected in thepositive direction on the x axis so that the position W1 of the wafer20A is irradiated. Since the moving speed of the mask 10 is VMa, thedistance between M0 and M0 on the mask 10 is (VMa×ΔtM), and when thereduction ratio is at 1/4, the distance between W1 and W0 on the wafer20A will be (VMa×ΔtM)/4. In other words, the corrected deflectionquantity imparted by the deflector 43 is (VMa×ΔtM)/4 when expressed as adistance on the wafer 20A.

In the case illustrated in FIG. 9B, the electron beam EB is deflected inthe negative direction on the x axis so that the position W1 of thewafer 20A is irradiated. At this point, since the distance between W1and W2 on the wafer 20A is (VWa×ΔtW), the corrected deflection quantityimparted by the deflector 43 is -(VMa×ΔtM)/4. As a result, when ΔtM isnot equal to 0, and ΔtW is not equal to 0,

    (corrected deflection quantity)=(vm×Δtm)/4-(vw×Δtw)(8)

By performing such corrected deflection, the pattern image is projectedat a specific position on the wafer 20A, thus, preventing any blurring.

It is to be noted that on the mask 10, the direction of positions atwhich the exposure time point is late, i.e., to the right in the figure,is designated the positive direction, and the same principle applies tothe direction of positions on the wafer 20A with the left side of thefigure designated as the positive direction, the reverse of thedirection on the mask 10.

Next, in reference to FIG. 10, a method for preventing blurring ofprojection patterns caused by deviation of the irradiation position ofthe electron beam EB on the mask 10 is explained. As an example, asituation in which a irradiation position deviation occurs because themask 10 and the wafer 20A are not in synchronization is considered. Thebroken line 10' indicates the mask position when the mask 10 and thewafer 20A are in synchronization. The position M1 of the mask 10' isirradiated by the electron beam EB and after passing through thatposition, the position W1 of the wafer 20A is irradiated by the electronbeam EB.

However, if the mask 10 is not in synchronization, the position W1 ofthe wafer 20A is irradiated by the electron beam EB by which theposition M0 of the mask 10 has been irradiated. When this happens, theirradiation position deviation on the mask 10 is

    (M0-M1)<0                                                  (9)

and the electron beam EB is deviated in the negative direction on themask 10. Because of this, the position W1 which is deviated by (M1-M0)/4in the positive direction from position W0 where it should be irradiatedon the wafer 20A is irradiated by the electron beam EB. As a result,blurring of the pattern image occurs.

In this case, since the direction of corrected deflection performed bythe deflector 43 is the opposite from the direction of this positionaldeviation, the quantity of corrected deflection is

    (quantity of corrected deflection)=(M0-M1)/4               (10)

By performing deflection in this manner, the image of the pattern atposition M0 on the mask 10 is projected at a specific position W0 on thewafer 20A. One should note that the exposure data are organized insequence by using the wafer coordinate values for reference.

While, in the projection system described above, a irradiation range 140that includes the small areas 110 is irradiated, as shown in FIG. 2A, bythe electron beam EB, which is shaped into a rectangular shape by thefirst aperture 34, the pattern in the small areas 110 may be projectedby continuously scanning a spot beam that is highly constricted(Gaussian Beam), as shown in FIG. 11. In FIG. 11, SB indicates a spotbeam, and the entirety of the irradiation range 140 is exposed bydeflecting the spot beam SB in the direction running at a right angle todirection YM' to perform scanning along the path B while continuouslymoving the mask 10 in direction YM'.

The present invention is not limited to the preferred embodimentsdescribed above and it may be implemented in a number of forms. Forinstance, while in the first embodiment the stage positions detected bythe laser interferometer position sensors 44 and 45 are differentiatedto determine the actual speeds VMa and VWa of a mask 10 and the wafer20A, a tacho-generator may be provided at the actuators 61 and 62 forthe stages 37 and 40 to detect the actual speeds VMa and VWa byutilizing electromotive force.

In the above described explanation, the mask stage 37, the wafer stage40, and the deflectors 36A, 36B, 41A, 41B and 43 are expressed on onecoordinate, for convenience. Actually, however, the image is rotated bythe electromagnetic lenses 38 and 39. Consequently, the directions ofthe x and y coordinate axes differ before and after the electromagneticlenses 38 and 39.

What is claimed is:
 1. A pattern projection method comprising:causing amask and a radiation sensitive substrate to make at least one continuousmovement to perform projections; and irradiating a plurality of smallareas contained within a specific range of said mask in time sequence bya charged particle beam to project a pattern in each of said small areasselectively onto one of a plurality of projection areas contained withina specific range of said radiation sensitive substrate while one of saidat least one continuous movement of said mask and one continuousmovement of said radiation sensitive substrate are being performed,wherein:during said irradiating, said charged particle beam to beconducted from said mask to said radiation sensitive substrate isdeflected in a direction of said one continuous movement of saidradiation sensitive substrate at a specific speed so that a relativespeed of an image of said pattern which is projected onto said radiationsensitive substrate and said radiation sensitive substrate becomessubstantially zero.
 2. A pattern projection method comprising:causing amask and a radiation sensitive substrate to make at least one continuousmovement to perform projection; and irradiating a plurality of smallareas contained within a specific range of said mask in time sequence bya charged particle beam to project a pattern in each of said small areasselectively onto one of a plurality of projection areas contained withina specific range of said radiation sensitive substrate while one of saidat least one continuous movement of said mask and one continuousmovement of said radiation sensitive substrate are being performed,wherein:a pattern to be projected onto a projection target area of saidradiation sensitive substrate is divided and formed on a plurality ofspecific small areas contained within a specific range of said mask. 3.A pattern projection method comprising:causing a mask and a radiationsensitive substrate to make at least one continuous movement to performprojections; and irradiating a plurality of small areas contained withina specific range of said mask in time sequence by a charged particlebeam to project a pattern in each of said small areas selectively ontoone of a plurality of projection areas contained within a specific rangeof said radiation sensitive substrate while one of said at least onecontinuous movement of said mask and one continuous movement of saidradiation sensitive substrate are being performed, wherein:(a) a patternto be projected onto a projection target area of said radiationsensitive substrate is divided and formed on a plurality of specificsmall areas contained within said specific range of said mask; (b) whena ratio of reduction of said pattern to be projected from said mask ontosaid radiation sensitive substrate is 1/M, a speed of said onecontinuous movement of said mask is set at (M×N) times a speed of saidcontinuous movement of said radiation sensitive substrate, said N beinga real number larger than 1; and (c) during said irradiating, saidcharged particle beam to be conducted from said mask to said radiationsensitive substrate is deflected in a direction of said one continuousmovement of said radiation sensitive substrate at a specific speed sothat a relative speed of said image of said pattern which is projectedonto said radiation sensitive substrate and said radiation sensitivesubstrate becomes substantially zero.
 4. A pattern projection methodaccording to claim 3, wherein:said charged particle beam is deflected insaid direction of said continuous movements by an electrostaticdeflector provided between said mask and said radiation sensitivesubstrate.
 5. A pattern projection method according to claim 3,wherein:during said continuous movements of said mask and said radiationsensitive substrate, speeds of said continuous movements or physicalquantities related to said speeds are detected and, based upon valuesthus detected, a speed of deflection of said charged particle beam insaid direction of said continuous movements is controlled.